What people have to remember about the fights is that, top speed does not win a fight.
Acceleration and climb rate (specially zoom climb) aswell as E retation wins a fight. The only thing top speed does for you is the ability to run away.
As the current MA environment has got quite a few LA7's flying around top speed doesn't matter all that much anymore either as there will usually be atleast one LA7 in the area who is capable of catching you no matter if you fly a 109, 190, P51, Jug or any other plane from either side (part from the perks).
Why is the Spit 16 and Spit 8 (well all spits) so dangerous? Because of the same reason the Ki84 is (only the Ki84 takes alot more time to master and fly well). Climb rate, acceleration, zoom climb. They are the perfect close combat dogfighters.
Are they overmodelled? I doubt it. The spit was infamouse for being an easy plane to fly.
Are the LW birds undermodelled? I think so. I also think that acceleration and dive acceleration, E retation and such is somewhat fubar, aswell as low speed handeling.
Are the US Birds overmodelled? Why do I think they are? Not because of top speed, not because of climb but mostly because of their stall characteristics. Without flaps they feel awsome to fly, extrmely friendly, much more then described in combat reports. Once a notch (or more) of flaps can be popped they go from awsome to unbelievable.
Just my opinion of course.
IMO the entire AH Acceleration FM feels off IMO, I know I am not the only one who's had Zekes outdive me in real fast 1944 planes (Dora, 109 G10/K4, P51, P47 etc, you name it). And that is going from same starting speed.
Of course, just my opinion.